Grinding machine

ABSTRACT

This invention relates to a grinding machine and, more particularly, to apparatus for bringing about various cross-feed motions in a machine for finishing workpieces by the abrasive process.

United States Patent Uhtenwoldt et a1. Mar. 21, 1972 54 GRINDING MACHINE[56] References Cited [72] inventors: Herbert R. Uhtenwoldt, Worcester;Wil- UNITED STATES PATENTS Iiam H. Grotewold, Holden Bruno E.

1 2,486,244 10/1949 Balslger et a1 ..51/l65.92 X wmeste" Mass 2,985,9885/1961 Johnson et a]. ..51/50 R [73] Assignee: The Heald MachineCompany, Worcester, 1 3,403,480 10/1968 Robillard .51/ 165.87 Mass.3,503,158 3/1970 Robillard et a1. ..5 l/165.8

3,561,168 21971 d l 22 Filed: Apr. 15, 1970 Rbmar 5 I 165 75 [21]APPLNQ; 23 Primary Examiner-Lester M.Swing1e Att0rney-N0rman S. Blodgett[52] U.S.Cl ..5l/165.89,5l/l65.8,5l/l65.9 57 ABSTRACT [51] Int. Cl..B24b 49/00 [58] Field of Search ..51/165.89, 165.77, [65.8, 165.81,Thls mvemlon relates to a s s machine and, more p ticularly, toapparatus for bringing about various cross-feed motions in a machine forfinishing workpieces by the abrasive process.

10 Claims, 2 Drawing Figures COMPENSATION COARSE 43 i ii POSITIONING 11|: FINE 44 POSITIONING PATENTEDHARZI I972 SHEET 1 [IF 2 INVENTORSHERBERT R. UHTENWOLDT WILLIAM H. GROTEWOLD BRUNO ESTRAUB BY ATTORNEYPAIENIEUHARZI I972 SHEET 2 [IF 2 BASE COMPENSATION FINE POSITIONINGCOARSE POSITIONING GRINDING MACHINE BACKGROUND OF THE INVENTION In theart of grinding and, particularly, internal grinding, it is necessary tomove the abrasive wheel relative to the workpiece through a cycle ofrather complex longitudinal and transverse motions. While thelongitudinal or traverse motions are relatively crude'and need not beperformed with any degree of accuracy, the transverse or feed motionsmust be done very accurately because they determine not only the size ofthe finish surface but its shape and finish. Any number of methods havebeen used for producing these transverse motions in the past. Generallyspeakingflhey have all been quite complicated and expensive.Furthermore, they have been difficult to adjust and to maintain. Theseand other difliculties experienced with the prior art devices have beenobviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide agrinding machine having a relatively simple and inexpensive cross-feedmeans.

Another object of this invention is the provision of a crossfeedapparatus for a grinding machine which is rugged in construction andwhich is capable of a long life of useful service with a minimum ofmaintenance.

A further object of the present invention is the provision of a feedmeans which is particularly adapted to operation by means of electricalpulses, thus permitting digital control.

A still further object of the invention is the provision of a grindingmachine with a cross-feed means, such that the feed slide can be movedto dress position'at any time in the cycle without disturbing thesetting of the feed mechanism.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partssetforth in the specification and covered by the claims appended hereto.

SUMMARY OF THE INVENTION A rod extension is mounted in the table inalignment with the rod and a slidable connection exists between the feedrod and the rod extension to permit relative axial sliding movementbetween them, but to cause them to rotate together. A means is mountedin the table to cause the sliding motion relative to the feed rod forgrinding feed and for dress retraction movements and means is alsomounted in the table and surrounding the extension to cause rotation ofthe extension and the rod for p roducing compensation and adjustingmovements of the table.

More specifically, a rotatable cam is mounted in the table for bringingabout the said sliding motion-to cause relative motion between thewheelhead table and the workhead transversely of the base to bring abouta grinding operationfand the cam is rotated by a stepping motor whichreceives feed pulses from a control apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention,however, may be best understood by reference toone of its structuralforms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a perspective view of a grinding machine embodying theprinciples of the present invention, and

FIG. 2 is a horizontal sectional view of the machine taken on the lineIIII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1,wherein are best shown' the general features of the invention, thegrinding machine, indicated generally by the reference numeral 10, isshown as being of the type known as a universal" grinding machine inthat it is not only capable of automatic production work, but also iscapable of being used as a toolroom machine for machining small lots ofworkpieces; the machine is of the type shown and described in the patentof Johnson et al., U.S. Pat. No. 2,985,988. It is provided with a base11 on which is mounted a workhead 12 having a dressing apparatus 30 andhaving a rotatable chuck 13 for carrying a workpiece 14. In thepreferred embodiment, the invention is shown as being set up as aninternal grinding machine to finish a bore in the work piece 14. On thebase is also mounted a wheelhead table 15 for carrying an abrasive wheel20. Mounted at the front of the table is a feed box 16. Mounted on thebase at the rear thereof is a control apparatus 17 connected by suitableelectrical cables 23 to the feed box 16. The control apparatus issimilar to that shown in the patent of Robillard U.S. Pat. No. 3,403,480and consists of digital equipment including logic circuits and countersto provide a feed stepping motor with electrical pulses. Also mounted onthe front of the control apparatus is a digi-switch readout-and-settingapparatus 18 similar to that shown in the patent application ofRobillard Ser. No. 720,912, filed Apr. 12, 1968, now U.S. Pat. No.3,561,168, dated Feb. 9, I971.

Referring now to FIG. 2, which shows the details of the cross-feedapparatus, it can be seen that the base 11 is connected to the wheelheadtable 15 by a feed rod 19. For the purposes of the description whichfollows, the feed box 16 will be considered as part of the table, sinceit is fastened to its forwardly directed surface and moves with it. Asis evident in the drawing, the rod 19 is mounted in the table 15 in sucha way that the table can slide relative to the base 11 and relative tothe rod 19 itself. The rotatable cam 21 is mounted in the table 15 forbringing about the said sliding motion. This is done to cause relativemotion between the wheelhead table 15 and the workhead 12 transverselyof the base to bring about a grinding operation.

The cam 21 is rotated by a stepping motor 22 which is connected by theflexible cable 23 to the control apparatus 17.

The cam engages and moves a cam follower 25 which is mounted on one endof a lever 24, the other end of which is pivotally fastened to the table15. An intermediate portion is pivotally fastened to the feed rod 19 bymeans of a pivot pin 26 to produce the sliding motion. The feed rod 19is fastened to the base 11 by a threaded connection consisting of a Ithreaded portion 27 of the rod threadedly engaging a nut-like element 28fastened to'the base. A reduced cylindrical portion 29 of the rod isslidably engaged in a bore 31 formed in the element 28 and pressurefluid access is provided through a passage 32 in the base. Rotation ofthe feed rod 19 produces relative axial movement between the rod and thebase and this serves to move the table 15 also.

A rod extension 33 is rotatably mounted in the table in alignment withthe rod 19 and is connected with it by means of pegs 34. These pegsprovide a slidable connection between the feed rod and the rod extensionto permit relative axial sliding movement between them but to cause themto rotate together. Surrounding the extension is a one-way clutch 35(details of 'which are not shown) which has an arm 36 extending radiallyselected side of thepiston 38. Pressure fluid is introduced to the frontside of the piston to produce a dress retraction movement on occasion ofthe table 15 relative to the base 11. The

' back end of the piston is then thrown to the rear of the bore 39 It ispossible to provide coarse positioning by the rotation of a plate 43mounted at the front of the feed box 16 and having a handle 44, therotation of the plate serving to rotate the extension 33. Similarly, forfine positioning, it is only necessary to rotate a dial knob 45 whichalso operates on the extension 33 and serves to rotate the feed rod 19.The fine positioning knob 45 operates through a differential gearapparatus 46 (the details of which are not shown) to rotate theextension 33 at a much slower rate than a similar rotation of the plate43.

OPERATION The operation of the apparatus will now be readily understoodin view of the above description. The workpiece 14 is set up in thechuck 13 and the workhead l2 drives the chuck and rotates the workpiecein the usual way. The abrasive wheel 20 is advanced longitudinally ofthe base 11 and transversely relative to the workpiece 14 by the usualcontrol apparatus under the regulation of the control apparatus 17. Allthe movements are displayed in the digi-switch apparatus 18, so that theoperator always knows where the abrasive wheel is located simply bylooking at the readout. In order to feed the abrasive wheel toward thesurface to be finished in the workpiece, the cam 21 is rotated by thestepping motor 22. This stepping motor receives pulses from the controlapparatus 17 and the pulses are counted and displayed on the apparatus18. Rotation of the cam pivots the lever 24 about its pivoted end andoperates through the pivot pin 26 to move the table rearwardly relativeto the rod 19. Pressure fluid exists in the passage 41 so that thepiston 38 is positioned toward the front of the bore 39 so that the pin26 urges the lever 24 and the cam follower 25 against the cam 21. Thegrinding portion of the cycle is terminated in the usual way by theengagement of the wheelhead table 15 with a switch or by a suitableindication from an in-process gage, or simply by the counting of thenumber of pulses reaching the stepping motor and displayed in thedigi-switch apparatus 18. However, this portion of the cycle isterminated, the stepping motor 22 receives negative pulses and operatesin the reverse direction to rotate the cam in the direction from whichit came; the lever 24 and the table 15 follow it in the forwarddirection. The wheel is retracted from the workpiece either for dress bythe dressing apparatus 30 or for termination of the cycle by introducingoil into the passage 42 which causes the table to move forwardly untilthe piston 38 engages the rearward end of the bore 39. It is interestingto note that dress can take place at any time and as many times asdesired during the cycle and the cam rotation is stopped until thedressing operation is completed. Thus, the wheelhead table is returnedto the same cross-feed position on the cam as before the dressing cyclestarted. Compensation is introduced through the motor 37, but, ofcourse, the diamond removes material from the wheel. This means that,even though the table is advanced rearwardly relative to the base 11,the wheel surface remains the same when the cam follower 25 againengages the cam 21.

In order to cause the dressing apparatus of the machine to remove asatisfactory amount of the wheel surface to renew it, it is necessary toprovide a compensation movement, and this is accomplished by rotatingthe rod 19 so that it advances closer to the base 11. Fluid pressure isintroduced into the motor 37 to reciprocate it and the angularto-and-fro motion of the arm 36 causes uni-directional rotation throughthe oneway clutch 35 of the extension 33. The extension, of course, iskeyed to the rod 1.9 by the pins 34 and, therefore, this causes rotationof the rod. Before every dressing cycle, the operation of thecompensating motor 37 will move the table and the wheel further to therear to allow the dressing diamond to remove a substantial portion ofthe abrasive wheel; the effective surface of the wheel for grinding, ofcourse, remains in the same plane in the well-known manner, this planebeing dictated by the position of the dressing diamond on the dressingapparatus 30. Initial adjustment or adjustments during successivegrinding cycles can be produced by use of the handle 44 rotating theplate 43 which operates directly on the extension 33, and rotates therod 19 and produces rearward movement of the table 15 in a directproportion. When it is desired to make fine adjustments, however, therotation of the knob 45 operates through the differential gear apparatus46 and produces considerably less than a full revolution of the rod 19for a full revolution of the knob 45. This permits fine adjustit isobvious that minor changes may be made in the fonn and construction ofthe invention without departing from the material spirit thereof. it isnot, however, desired to confine the invention to the exact form hereinshown and described, but it is desired to include all such as properlycome within the scope claimed.

The invention having been thus described, what is claimed as new anddesired to secure by Letters Patent is:

1. A grinding machine, comprising a. a base having a workhead mounted atone end,

b. a wheelhead table mounted at the other end,

c. a feed rod extending between the table and the base and being mountedin the table for longitudinal sliding motion relative thereto, and

d. a rotatable cam mounted in the table for bringing about the saidsliding motion to cause relative motion between the wheelhead table andthe workhead transversely of the base to bring about a grindingoperation.

2. A grinding machine as recited in claim 1, wherein the cam is rotatedby a stepping motor which receives feed pulses from a control apparatus.

3. A grinding machine as recited in claim 1, wherein the cam engages andmoves one end of a lever, the other end of which is pivotally fastenedto the table, and wherein an intermediate portion of the lever ispivotally fastened to the feed rod to produce the sliding motion.

4. A grinding machine as recited in claim 1, wherein the feed rod isfastened to the base by a threaded connection, so that rotation of thefeed rod produces relative axial movement between the rod and base.

5. A grinding machine as recited in claim 4, wherein a oneway clutchsurrounds the feed rod, an arm extends radially from the exterior of theclutch, and a reciprocable fluid motor engages the outer end of the armto produce incremental rotation of the rod to produce compensatingsliding movement of the table relative to the base.

6. A grinding machine as recited in claim 1, wherein the feed rod isprovided with a concentric piston which is slidable in a cylinder boreformed in the table, and wherein means is provided to introduce pressurefluid into the bore selectively on one side of the piston to producedress retraction movement of the table relative to the base or to theother for grind- 7. A grinding machine, comprising a. a base,

b. a table mounted on the base for sliding motion thereover,

c. a feed rod extending between the table and the base and being mountedin the table for rotation and axial sliding motion relative thereto,

d. a rod extension mounted in the table in alignment with the rod,

e. a slidable connection between the feed rod and the rod extension topermit relative axial sliding movement between them but to cause them torotate together,

f. a first means mounted in the table to cause the sliding motionrelative to the feed rod for grinding feed and for dress retractionmovements, and

g. a second means mounted in the table and surrounding the extension tocause rotation of the extension and the rod for producing compensationand adjusting movements of the table.

8. A grinding machine as recited in claim 7, wherein the said firstmeans is a cam-operated lever and a fluid motor.

9. A grinding machine as recited in claim 7, wherein the said secondmeans is a fluid motor operating on the extension through a one-wayclutch concentric with the extension and a rotatable plate having anoperating handle and a central knob.

the said sliding motion to cause relative motion between the wheelheadtable and the workhead transversely of the base to bring about agrinding operation, and

f. means operative at any time in the grinding operation to stop therotation of the cam and move the wheelhead table to a dress position tobring the abrasive wheel into operative engagement with the dressingapparatus.

1. A grinding machine, comprising a. a base having a workhead mounted atone end, b. a wheelhead table mounted at the other end, c. a feed rodextending between the table and the base and being mounted in the tablefor longitudinal sliding motion relative thereto, and d. a rotatable cammounted in the table for bringing about the said sliding motion to causerelative motion between the wheelhead table and the workheadtransversely of the base to bring about a grinding operation.
 2. Agrinding machine as recited in claim 1, wherein the cam is rotated by astepping motor which receives feed pulses from a control apparatus.
 3. Agrinding machine as recited in claim 1, wherein the cam engages andmoves one end of a lever, the other end of which is pivotally fastenedto the table, and wherein an intermediate portion of the lever ispivotally fastened to the feed rod to produce the sliding motion.
 4. Agrinding machine as recited in claim 1, wherein the feed rod is fastenedto the base by a threaded connection, so that rotation of the feed rodproduces relative axial movement between the rod and base.
 5. A grindingmachine as recited in claim 4, wherein a one-way clutch surrounds thefeed rod, an arm extends radially from the exterior of the clutch, and areciprocable fluid motor engages the outer end of the arm to produceincremental rotation of the rod to produce compensating sliding movementof the table relative to the base.
 6. A grinding machine as recited inclaim 1, wherein the feed rod is provided with a concentric piston whichis slidable in a cylinder bore formed in the table, and wherein means isprovided to introduce pressure fluid into the bore selectively on oneside of the piston to produce dress retraction movemeNt of the tablerelative to the base or to the other for grinding.
 7. A grindingmachine, comprising a. a base, b. a table mounted on the base forsliding motion thereover, c. a feed rod extending between the table andthe base and being mounted in the table for rotation and axial slidingmotion relative thereto, d. a rod extension mounted in the table inalignment with the rod, e. a slidable connection between the feed rodand the rod extension to permit relative axial sliding movement betweenthem but to cause them to rotate together, f. a first means mounted inthe table to cause the sliding motion relative to the feed rod forgrinding feed and for dress retraction movements, and g. a second meansmounted in the table and surrounding the extension to cause rotation ofthe extension and the rod for producing compensation and adjustingmovements of the table.
 8. A grinding machine as recited in claim 7,wherein the said first means is a cam-operated lever and a fluid motor.9. A grinding machine as recited in claim 7, wherein the said secondmeans is a fluid motor operating on the extension through a one-wayclutch concentric with the extension and a rotatable plate having anoperating handle and a central knob.
 10. A grinding machine, comprisinga. a base having a workhead mounted at one end, b. a dressing apparatusassociated with the workhead, c. a wheelhead table mounted at the otherend and carrying an abrasive wheel, d. a feed rod extending between thetable and the base and being mounted in the table for longitudinalsliding motion relative thereto, e. a rotatable cam mounted in the tablefor bringing about the said sliding motion to cause relative motionbetween the wheelhead table and the workhead transversely of the base tobring about a grinding operation, and f. means operative at any time inthe grinding operation to stop the rotation of the cam and move thewheelhead table to a dress position to bring the abrasive wheel intooperative engagement with the dressing apparatus.